== Caffeine and Alcohol ==
The scientific evidence shows that caffeine is generally not a diuretic <ref name="ref5"/><ref name="ref14"/><ref name="ref15"/>. Previous studies have shown that if you don't normally take caffeine and then get a large dose, there is some diuretic effect. However normal intakes of caffeine by non-users and use by regular users is not a diuretic <ref name="ref16"/>. (If you urinate more because you drink a 20oz Latte, it is because of the 20oz of fluid, not the caffeine.)
Alcohol is another story; drinking anything stronger than 2% will cause dehydration. Because alcohol takes 36 hours to clear the body, it should be avoided for 48 hours before you wish to avoid impaired performance <ref name="ref5"/>.
== Muscle Cramps ==
== Blisters and black toe nails ==
Dehydration reduces body weight, which can reduce the size of your feet. This in turn changes the fit of your shoes, causing blisters. Hyponatremia can cause swelling, which increases the size of your feet and can cause blisters. Both conditions can also increase the chance of black toe nails.
== References ==
<ref name="ref1">Exercise-Associated Hyponatremia